Automated doors, for instance sectional overhead doors, sliding doors or roll doors, typically comprise a motor connected to a door drive shaft for moving the door between an open and a closed position, and vice versa. For a sliding door, the door drive shaft may for instance be the shaft provided with a reel or sprocket for moving a belt that displaces the door. For roll doors, the door drive shaft may be the shaft the roll door is wrapped around in the opened position.
The motor typically is provided with an integrated encoder device that determines the rotational position of the motor shaft. The rotational position of the motor shaft can be related to the position of the door. Calibration is usually required to determine which rotational position corresponds to a fully opened position and the closed position, intermediate positions may be interpolated. The information from the encoder can be used by a controlling unit connected to the encoder to operate the driving motor. For instance, the motor would be stopped when the fully closed or opened position is reached.